1. Field of the Invention
The invention is directed to an improved actuator unit for controlling movement of a throttle body.
2. Description of the Prior Art
German Published, Nonexamined Patent Application DE-A 195 25 510 and U.S. Pat. No. 5,672,818 show an actuator unit with a control motor and a throttle body. In the known actuator unit, between the control motor and the throttle body, which takes the form of a throttle valve, there is always the same gear ratio in every position. As is now known, the torque required at the throttle body is of various magnitudes in the various positions of the throttle body. For this reason, the torque of the control motor must be designed to be high enough that this torque suffices in every position of the throttle body. The control motor must also be designed such that in all the adjustment ranges, the throttle valve can be adjusted fast enough. Both requirements necessitate a powerful and thus relatively large, expensive control motor. This makes the overall actuator unit relatively large and requires a relatively large amount of installation space.